BETHESDA, Md., Aug. 27 (UPI) -- Interrupting large periods of sedentary activity in children for brief intervals of exercise could help to prevent the development of diabetes, cardiovascular disease and cancer, according to a small study.
More than one-third of children in the United States are overweight or obese, with the average American child spending about 6 hours a day either sitting or reclining, putting them at risk for a wide range of conditions.
"We know that 30 minutes or more of moderate physical activity benefits children's health," said the Dr. Jack A. Yanovski, chief of the National Institute of Child Health and Human Development's section on growth and obesity, in a press release. "It can be difficult to fit longer stretches of physical activity into the day. Our study indicates that even small activity breaks could have a substantial impact on children's long-term health."
Researchers thought short bursts of activity would help children based on previous research showing that walking a mile in 15 or 20 minutes can lower glucose and insulin levels in adults.
To test the theory, researchers recruited 28 healthy, normal-weight children who were assigned at random to two groups -- one group remained seated for 3 hours watching television, reading or doing something else that kept them mostly sedentary, while the other group took 3 minute breaks every 30 minutes to walk on a treadmill. Between 7 and 28 days later, the children took part in the study again, switching groups.
The children were asked to take an oral glucose tolerance test after each of the two sessions, which allowed researchers to measure how fast their bodies absorbed glucose and how much insulin their bodies produced. On the days they walked, the children had 7 percent lower blood glucose levels than on the day they'd spent sedentary, as well as 32 percent lower insulin levels.
"Sustained sedentary behavior after a meal diminishes the muscles' ability to help clear sugar from the bloodstream," said Dr. Britni Belcher, a cancer prevention fellow in the National Cancer Institute's Health Behavior Research Branch. "That forces the body to produce more insulin, which may increase the risk for beta cell dysfunction that can lead to the onset of type 2 diabetes. Our findings suggest even short activity breaks can help overcome these negative effects, at least in the short term."